CA1064993A - Spring cage mechanism - Google Patents
Spring cage mechanismInfo
- Publication number
- CA1064993A CA1064993A CA272,944A CA272944A CA1064993A CA 1064993 A CA1064993 A CA 1064993A CA 272944 A CA272944 A CA 272944A CA 1064993 A CA1064993 A CA 1064993A
- Authority
- CA
- Canada
- Prior art keywords
- pistons
- head
- contour
- bore
- pair
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Transmission Of Braking Force In Braking Systems (AREA)
Abstract
SPRING CAGE MECHANISM
ABSTRACT OF THE DISCLOSURE
A caging apparatus for holding a spring between a first retainer and a second retainer to separate a first piston from a second piston to size a pressurizing chamber in a master cylinder.
ABSTRACT OF THE DISCLOSURE
A caging apparatus for holding a spring between a first retainer and a second retainer to separate a first piston from a second piston to size a pressurizing chamber in a master cylinder.
Description
4~193 This invention relates to a means for separating a first piston from a second piston in a tAndem master cylinder.
U.S. P~tent No. 3,818,706 dlscloses a brakin~ system with a tandem ~ast~er cyllnder having a piston positioned in a bore by first and second springs to establish first and second pressuri~ing chambers therein. The volumetric size of the first and second pressurizing chamber are matched to the actuation fluid requirement of drum brakes and disc brakes located in the braking system. If the first and second springs are not matched, a delay in actuation between the drum brakes and disc brakes can result.
To prevent such a delay, it was found that by caging one of the springs, the size of the first and secondary chambers could be positively established.
U.S. Patent No. 3,686,8b4 discloses a tandem master cylinder with`a typical caged spring for establishing the position of a first piston relative to a second piston. The caged spring has a retainer which is threadedly attached to a second piston by a long bolt. However, under some con-ditions of operation the threaded connection has failed and allowed the second piston to shift ln the bore and thereby change the operating characterlstics o the tandem master cyllnder.
The present invention resides in a master cylinder having a housing defining a bore therein with a pair of plstons slldably mounted in the bore, the pistons cooperating wlth one another and the housing to create a first pressure chamber between corresponding ends of the pistons and a second pressure chamber between the other end of one of the pistons and the end of ~he bore. Cage means is provided in the first chamber yieldably-maintaining each of the ,, ~; , ~ kh~
6~993 pistons a predetermlned distance from the other piston, the cage means havlng a first retainer with a conlcal body extending from a base, the base engaging one of the pair o~ pistons. The conical body has an inwardly pro;ecting lip for establishing an axial opening. The cage means has a disc for engaging the other of the pair of pistons, the disc having a first contour and a concentric second contour with a first diameter opening located adjaceat the first contour and a second diamater opening located in the axial center of the second contour. The first diameter opening is connected to the second diameter opening by a slot. The cage means has a spring that surrounds the conical body.
One end of the spring engages the first contour of the disc, the spring moving the first retainer and the disc away from each other, The first contour malntains the spring ln a substantially radlal position in the bore, and the cage means has ~ stem w:Lth a first head and a second head, the first head being larger than the axial opening 9 and the second head being larger than the second diameter opening in the disc. The first head engages the lip on the first retainer and the second head is located in the second diameter opening in the axial center of the second contour ln the disc after passing through the first diameter opening and free~y moving radlally ln the slot, l`lle second head en8~ges the secolld conto~r when the pair of pistons move relative to each other within the bore to hold the stem in the axial ccnter o~ the bore.
It is therefore the ob~ect of this invention to provide a master cylinder with a caging means which separates a first plston from a second piston to establish the volume of first and second pressurizing chambers located in the kh/J~
~6~69~93 master cylin~er.
It is another obJect of this lnvention to provide a means for fastening a stem between a first retainer and n second retalner to hold a 3prLng in a caged position.
It ls a still urther object of this invention for providing a fastener means having an opening with a first diameter section offset from a second diameter section to permit a head on a stem to pass through the first diameter section and thereafter be shifted to the second diameter section to retain a resilient means in a caged condition.
These and other objects will be apparent from reading this specification and viewing the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic illustration of a braking system including a sectional view of a master cylinder incorporating the teachings of my invent:lon; and Figure 2 is a sectional view taken along lines 2-2 of Figure 1.
- 3a -.,~
s kh~
1~64g93 DETAILED DESCRIPTION OF THE DRAWINGS
The braking system lO has a master cylinder 12 connected to front wheel brake~ 14 ani rear wheel brakes 16 by conduits 18 and 20 respectively. A push rod 22 and a pedal 24 provide a linear input for moving a first piston 26 and a second piston 28 in bore 30 of the m~ster cylinder 12 .o create the energizing force. The position of the second piston 28 in bore 30 is established by a ca~lng means 32. The position of the second ptston 28 determJnes thc slze of a fTrst pressurizin~ chamber 34 and a second pressurtzlng chamber 36 1n bore 30. The size of the first pressurizing chamber 34 and the second pressurizing chamber 36 determines the volume of fluid capable of betng supplied to the front wheel disc brakes 14 and the rear wheel drum brakes 16 through the conduits 18 and 20.
Thc first piston 26 has a bearing surface 38 with a diameter which substant;ally f~lls the bore 30 and separates a compensator port 40 from a relief port 42. The fTrst piston 26 has a shoulder 4fl which cooper-ates with bearing surface 38 to hold the seal 44 in a fixed position wTthin bore 30. A seal 44 prevents communlcation of fluid between the first pressurizing chamber 34 and the relief chamber 46.
The second piston 28 has a cylindrical body 50 with a bearing surface 52. The bearing surface 52 has a diameter substantTally equal to bore 30 and separates a compensator port 54 from a relief port 56.
shoulder 58 on the cyllndrlcal body 50 forms a g~roove 60 with bearing surface 52. A seal 62 located In ~roove 60 prevents fluld communlcation between the second pressurlzlng chamber 36 and the rellef chamber 64. A
return spring 66 located between the bottom 61 oF bore 30 and shoulder 58 holds thc second plston 28 agalnst the caglng means 32 and the ft rst piston 26 agalnst stop 68 The caging means 32 Includes a ~Irst retalner 70 connected to a second retainer 72 by a stem 74 for holding a spring or resilient means 76 In a caged condltinn.
1~6~9~3 The first retainer 70 has a base 78 which abuts shoulder 48 on the first piston 26 and a conical or cylindrical body 80 which extends into the first pressurizing chamber 3~. The cylindri-cal body 80 has an inwardly projecting lip 82 -Eor forming an axial opening 84.
The second retainer 72 includes a disc 86, see Figure
U.S. P~tent No. 3,818,706 dlscloses a brakin~ system with a tandem ~ast~er cyllnder having a piston positioned in a bore by first and second springs to establish first and second pressuri~ing chambers therein. The volumetric size of the first and second pressurizing chamber are matched to the actuation fluid requirement of drum brakes and disc brakes located in the braking system. If the first and second springs are not matched, a delay in actuation between the drum brakes and disc brakes can result.
To prevent such a delay, it was found that by caging one of the springs, the size of the first and secondary chambers could be positively established.
U.S. Patent No. 3,686,8b4 discloses a tandem master cylinder with`a typical caged spring for establishing the position of a first piston relative to a second piston. The caged spring has a retainer which is threadedly attached to a second piston by a long bolt. However, under some con-ditions of operation the threaded connection has failed and allowed the second piston to shift ln the bore and thereby change the operating characterlstics o the tandem master cyllnder.
The present invention resides in a master cylinder having a housing defining a bore therein with a pair of plstons slldably mounted in the bore, the pistons cooperating wlth one another and the housing to create a first pressure chamber between corresponding ends of the pistons and a second pressure chamber between the other end of one of the pistons and the end of ~he bore. Cage means is provided in the first chamber yieldably-maintaining each of the ,, ~; , ~ kh~
6~993 pistons a predetermlned distance from the other piston, the cage means havlng a first retainer with a conlcal body extending from a base, the base engaging one of the pair o~ pistons. The conical body has an inwardly pro;ecting lip for establishing an axial opening. The cage means has a disc for engaging the other of the pair of pistons, the disc having a first contour and a concentric second contour with a first diameter opening located adjaceat the first contour and a second diamater opening located in the axial center of the second contour. The first diameter opening is connected to the second diameter opening by a slot. The cage means has a spring that surrounds the conical body.
One end of the spring engages the first contour of the disc, the spring moving the first retainer and the disc away from each other, The first contour malntains the spring ln a substantially radlal position in the bore, and the cage means has ~ stem w:Lth a first head and a second head, the first head being larger than the axial opening 9 and the second head being larger than the second diameter opening in the disc. The first head engages the lip on the first retainer and the second head is located in the second diameter opening in the axial center of the second contour ln the disc after passing through the first diameter opening and free~y moving radlally ln the slot, l`lle second head en8~ges the secolld conto~r when the pair of pistons move relative to each other within the bore to hold the stem in the axial ccnter o~ the bore.
It is therefore the ob~ect of this invention to provide a master cylinder with a caging means which separates a first plston from a second piston to establish the volume of first and second pressurizing chambers located in the kh/J~
~6~69~93 master cylin~er.
It is another obJect of this lnvention to provide a means for fastening a stem between a first retainer and n second retalner to hold a 3prLng in a caged position.
It ls a still urther object of this invention for providing a fastener means having an opening with a first diameter section offset from a second diameter section to permit a head on a stem to pass through the first diameter section and thereafter be shifted to the second diameter section to retain a resilient means in a caged condition.
These and other objects will be apparent from reading this specification and viewing the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic illustration of a braking system including a sectional view of a master cylinder incorporating the teachings of my invent:lon; and Figure 2 is a sectional view taken along lines 2-2 of Figure 1.
- 3a -.,~
s kh~
1~64g93 DETAILED DESCRIPTION OF THE DRAWINGS
The braking system lO has a master cylinder 12 connected to front wheel brake~ 14 ani rear wheel brakes 16 by conduits 18 and 20 respectively. A push rod 22 and a pedal 24 provide a linear input for moving a first piston 26 and a second piston 28 in bore 30 of the m~ster cylinder 12 .o create the energizing force. The position of the second piston 28 in bore 30 is established by a ca~lng means 32. The position of the second ptston 28 determJnes thc slze of a fTrst pressurizin~ chamber 34 and a second pressurtzlng chamber 36 1n bore 30. The size of the first pressurizing chamber 34 and the second pressurizing chamber 36 determines the volume of fluid capable of betng supplied to the front wheel disc brakes 14 and the rear wheel drum brakes 16 through the conduits 18 and 20.
Thc first piston 26 has a bearing surface 38 with a diameter which substant;ally f~lls the bore 30 and separates a compensator port 40 from a relief port 42. The fTrst piston 26 has a shoulder 4fl which cooper-ates with bearing surface 38 to hold the seal 44 in a fixed position wTthin bore 30. A seal 44 prevents communlcation of fluid between the first pressurizing chamber 34 and the relief chamber 46.
The second piston 28 has a cylindrical body 50 with a bearing surface 52. The bearing surface 52 has a diameter substantTally equal to bore 30 and separates a compensator port 54 from a relief port 56.
shoulder 58 on the cyllndrlcal body 50 forms a g~roove 60 with bearing surface 52. A seal 62 located In ~roove 60 prevents fluld communlcation between the second pressurlzlng chamber 36 and the rellef chamber 64. A
return spring 66 located between the bottom 61 oF bore 30 and shoulder 58 holds thc second plston 28 agalnst the caglng means 32 and the ft rst piston 26 agalnst stop 68 The caging means 32 Includes a ~Irst retalner 70 connected to a second retainer 72 by a stem 74 for holding a spring or resilient means 76 In a caged condltinn.
1~6~9~3 The first retainer 70 has a base 78 which abuts shoulder 48 on the first piston 26 and a conical or cylindrical body 80 which extends into the first pressurizing chamber 3~. The cylindri-cal body 80 has an inwardly projecting lip 82 -Eor forming an axial opening 84.
The second retainer 72 includes a disc 86, see Figure
2, with an opening having a first diameter section 88 offset from a second smaller diameter section 90 by an interconnecting slot 89. A first contour 92 on disc 86 forms a guide for holding one end of spring 76 in substantially a fixed position in bore 30.
A second annular contour 94 on disc 86 provides a barrier for holding the stem 74 in an axial position with respect to bore 96 in the second piston 28.
The stem 74 has a first head 98 located on a first end 97 of a cylindrical body 75 and a second head 100 located on a second end 99 of the cylindrical body 75. The first head 98 has a larger diameter than the second head 100. l'he diameter of the second head 100 is substantially equal to axial opening 84 in the first retainer 70 and -the first diameter section 88 in disc 86.
MODE OF ASSEMBLY OF THE CAGING MEANS
. . _ .
The spring 76 is located on base 78 of -the first re-tainer 70. The second head 100 on stem 74 is passed through open-ing 84 and the first head 98 brought into engagement w.ith lip 82.
The disa ~6 1~ loc~ted on th~ end o~ ~the sprin~ 76 by contour 92.
A compressive force is applied to the first retainer 70 and the second retainer 72 to compress spring 76. When a sufficient compr~iv~ force is applied, the second head 100 passes through the first diameter section 88. Thereafter, the second head 100 is shifted through slot 89 to the axial section 90 and the compressive force is released. The second contour 94 holds the stem 74 in the center of the disc 86. The length of stem 74 determines the length of the caging means 32 and the volumetric size oE the pressurizing chambers in a master cylinder. In order to change the size relation-ship between a first chamber and second chamber in a master cylinde.r 64~3193 all that is required is -to change the stem 74 in the caging means 32.
MODE OF OPERATION OF THE EMBODIM~NT
________________ When an operator applies an input force to pedal 24, push rod 22 moves the first piston 26 in bore 30 and produces a - firs-t pressurizing ~orce in chamber 34. Movement of the ~irst piston 26 is transmitted through caging means 32 into the second piston 28. When the second piston 28 moves pas-t compensator port 54, a second pressurizing force develops in the second chamber 36.
As the first and second pressurizing forces increase, spring 76 is comp~essed to allow the first piston 26 to move toward the second piston 28 at a different rate than the movement of the second piston 28 toward the end 61 of bore 30. Relative movement between the first piston 26 and the second piston 28, eliminates the restraining forces on the stem 74. At this point, s-tem 7~ is free to move axially with the confines of bore 30. However, bore 96 engages head 98 to prevent any lateral movement and maintain the stem in a fixed axial position with respect to bore 30. When the spring 76 is completely collapsed, end 102 on the ~irst piston 20 26 engages head 98 and moves the second head 100 on stem 7~ against the bottom of bore 96 to manually move the second piston 28 in the second chamber 36 and further pressurize the fluid contained therein.
Upon termination o~ the input ~'orce, spring 76 ~oves the ~irst pisto~n 26 and the second piston 28 away from each other and return spring 66 again seats the first piston 26 in stop 68.
Thus, the caging means 32 makes it possible to provide a means of establishing the size o~ the ~irst pressurizing chamber without physically connecting the first piston 26 to the second piston 28.
A second annular contour 94 on disc 86 provides a barrier for holding the stem 74 in an axial position with respect to bore 96 in the second piston 28.
The stem 74 has a first head 98 located on a first end 97 of a cylindrical body 75 and a second head 100 located on a second end 99 of the cylindrical body 75. The first head 98 has a larger diameter than the second head 100. l'he diameter of the second head 100 is substantially equal to axial opening 84 in the first retainer 70 and -the first diameter section 88 in disc 86.
MODE OF ASSEMBLY OF THE CAGING MEANS
. . _ .
The spring 76 is located on base 78 of -the first re-tainer 70. The second head 100 on stem 74 is passed through open-ing 84 and the first head 98 brought into engagement w.ith lip 82.
The disa ~6 1~ loc~ted on th~ end o~ ~the sprin~ 76 by contour 92.
A compressive force is applied to the first retainer 70 and the second retainer 72 to compress spring 76. When a sufficient compr~iv~ force is applied, the second head 100 passes through the first diameter section 88. Thereafter, the second head 100 is shifted through slot 89 to the axial section 90 and the compressive force is released. The second contour 94 holds the stem 74 in the center of the disc 86. The length of stem 74 determines the length of the caging means 32 and the volumetric size oE the pressurizing chambers in a master cylinder. In order to change the size relation-ship between a first chamber and second chamber in a master cylinde.r 64~3193 all that is required is -to change the stem 74 in the caging means 32.
MODE OF OPERATION OF THE EMBODIM~NT
________________ When an operator applies an input force to pedal 24, push rod 22 moves the first piston 26 in bore 30 and produces a - firs-t pressurizing ~orce in chamber 34. Movement of the ~irst piston 26 is transmitted through caging means 32 into the second piston 28. When the second piston 28 moves pas-t compensator port 54, a second pressurizing force develops in the second chamber 36.
As the first and second pressurizing forces increase, spring 76 is comp~essed to allow the first piston 26 to move toward the second piston 28 at a different rate than the movement of the second piston 28 toward the end 61 of bore 30. Relative movement between the first piston 26 and the second piston 28, eliminates the restraining forces on the stem 74. At this point, s-tem 7~ is free to move axially with the confines of bore 30. However, bore 96 engages head 98 to prevent any lateral movement and maintain the stem in a fixed axial position with respect to bore 30. When the spring 76 is completely collapsed, end 102 on the ~irst piston 20 26 engages head 98 and moves the second head 100 on stem 7~ against the bottom of bore 96 to manually move the second piston 28 in the second chamber 36 and further pressurize the fluid contained therein.
Upon termination o~ the input ~'orce, spring 76 ~oves the ~irst pisto~n 26 and the second piston 28 away from each other and return spring 66 again seats the first piston 26 in stop 68.
Thus, the caging means 32 makes it possible to provide a means of establishing the size o~ the ~irst pressurizing chamber without physically connecting the first piston 26 to the second piston 28.
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a master cylinder:
a housing defining a bore therewithin;
a pair of pistons slidably mounted in said bore, said pistons cooperating with one another and said housing to create a first pressure chamber between corresponding ends of said pistons and a second pressure chamber between the other end of one of said pistons and the end of the bore; and cage means in said first chamber yieldably main-taining each of said pistons a predetermined distance from the other piston, said cage means having a first retainer with a conical body extending from a base, said base en-gaging one of said pair of pistons, said conical body having an inwardly projecting lip for establishing an axial opening, said cage means having a disc for engaging the other of said pair of pistons, said disc having a first contour and a concentric second contour with a first diameter opening located adjacent said first contour and a second diameter opening located in the axial center of said second contour, said first diameter opening being connected to said second diameter opening by a slot, said cage means having a spring that surrounds said conical body, one end of the spring en-gaging the first contour on said disc, said spring moving said first retainer and said disc away from each other, said first contour maintaining said spring in a substantially radial position in said bore, said cage means having a stem with a first head and a second head, said first head being larger than said axial opening, said second head being larger than said second diameter opening in said disc, said first head engaging said lip on said first retainer and said second head being located in the second diameter opening in the axial center of the second contour in the disc after passing through said first diameter opening and freely moving radially in said slot, said second head en-gaging said second contour when the pair of pistons move relative to each other within said bore to hold said stem in the axial center of said bore.
a housing defining a bore therewithin;
a pair of pistons slidably mounted in said bore, said pistons cooperating with one another and said housing to create a first pressure chamber between corresponding ends of said pistons and a second pressure chamber between the other end of one of said pistons and the end of the bore; and cage means in said first chamber yieldably main-taining each of said pistons a predetermined distance from the other piston, said cage means having a first retainer with a conical body extending from a base, said base en-gaging one of said pair of pistons, said conical body having an inwardly projecting lip for establishing an axial opening, said cage means having a disc for engaging the other of said pair of pistons, said disc having a first contour and a concentric second contour with a first diameter opening located adjacent said first contour and a second diameter opening located in the axial center of said second contour, said first diameter opening being connected to said second diameter opening by a slot, said cage means having a spring that surrounds said conical body, one end of the spring en-gaging the first contour on said disc, said spring moving said first retainer and said disc away from each other, said first contour maintaining said spring in a substantially radial position in said bore, said cage means having a stem with a first head and a second head, said first head being larger than said axial opening, said second head being larger than said second diameter opening in said disc, said first head engaging said lip on said first retainer and said second head being located in the second diameter opening in the axial center of the second contour in the disc after passing through said first diameter opening and freely moving radially in said slot, said second head en-gaging said second contour when the pair of pistons move relative to each other within said bore to hold said stem in the axial center of said bore.
2. In a master cylinder, as recited in claim 1, wherein one of said pair of pistons includes:
an annular projection for engaging said first head when the relative movement between the pair of pistons causes the spring to collapse, said annular projection directly transmitting an input force into the first head for moving the pair of pistons.
an annular projection for engaging said first head when the relative movement between the pair of pistons causes the spring to collapse, said annular projection directly transmitting an input force into the first head for moving the pair of pistons.
3. In the master cylinder, as recited in claim 2, wherein the length of said stem establishes the relationship between the pair of pistons to size said first chamber.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US67121476A | 1976-03-29 | 1976-03-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1064993A true CA1064993A (en) | 1979-10-23 |
Family
ID=24693584
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA272,944A Expired CA1064993A (en) | 1976-03-29 | 1977-03-01 | Spring cage mechanism |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS52118173A (en) |
| AR (1) | AR210031A1 (en) |
| BR (1) | BR7701847A (en) |
| CA (1) | CA1064993A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4939901A (en) * | 1987-10-24 | 1990-07-10 | Alfred Teves Gmbh | Tandem master cylinder with piston stops and central valves |
-
1977
- 1977-03-01 CA CA272,944A patent/CA1064993A/en not_active Expired
- 1977-03-25 BR BR7701847A patent/BR7701847A/en unknown
- 1977-03-29 AR AR26702577A patent/AR210031A1/en active
- 1977-03-29 JP JP3407877A patent/JPS52118173A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4939901A (en) * | 1987-10-24 | 1990-07-10 | Alfred Teves Gmbh | Tandem master cylinder with piston stops and central valves |
Also Published As
| Publication number | Publication date |
|---|---|
| BR7701847A (en) | 1978-01-17 |
| JPS52118173A (en) | 1977-10-04 |
| AR210031A1 (en) | 1977-06-15 |
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